1. Statement of the Technical Field
The invention concerns clamping mechanisms, and more particularly, clamping mechanisms for fastening printed circuit boards or printed circuit cards to chassis.
2. Description of the Related Art
Traditionally, circuit card clamps have been used for fastening circuit cards within a slot of a chassis such as a heat exchanger, heat sink, or cold plate. For example, U.S. Pat. No. 4,775,260 to Kecmer (hereinafter “Kecmer”), U.S. Pat. No. 5,071,013 to Peterson (hereinafter “Peterson”), and U.S. Pat. No. 4,298,904 to Koenig (hereinafter “Koenig”) describe circuit card clamps consisting of threaded rods with wedge-shaped bodies disposed thereon. A circuit card clamp coupled to a circuit card can be inserted into a chassis slot. Subsequently, the threaded rod can be rotated with a tool (i.e., torque wrench) in order to shorten the length of the circuit card clamp. By shortening the circuit card clamp, the wedge-shaped bodies are compressed thereby creating an increase in the circuit card clamp's width. As a result, a clamping force is exerted by the circuit card clamp securing the circuit card to the chassis.
The above described circuit card clamps suffer from certain drawbacks. For example, if the circuit card clamp is actuated so that it exerts a clamping force on the circuit card, then the circuit card is in contact with at least one wall of the chassis. In this scenario, thermal energy generated by the circuit card is passed to the chassis, thereby providing conduction cooling. However, the conduction cooling provided by such a clamp configuration is insufficient for Versa Module Eurcard (VME) cards having a fifty (50) watts power dissipation design. Further, the clamping forces exerted by the above described circuit card clamps are insufficient for adequately fastening a circuit card to a chassis to prevent loosening of the circuit card when exposed to external forces (such as vibration forces).
In view of the forgoing, there is a need for a wedge assembly that is able to provide improved conduction cooling (or thermal performance). The wedge assembly also needs to provide an improved clamping force for adequately fastening a circuit card to a chassis.